The invention relates to an x-ray diagnostic installation comprising an image intensifier television chain which exhibits an x-ray image intensifier, a television pickup device with an optoelectronic image converter and a monitor, and in which the transmission proceeds according to the interlaced method.
It is generally known to employ television technological means for the observation of an x-ray image. In order to generate the television signal, a video pickup tube has been employed up to the present time, whose output signal is amplified and displayed on a monitor. The camera tube is customarily coupled to the x-ray image intensifier with an optical device whose output image is converted into electrical signals.
Recently, brought about by the advances realized in the semiconductor field, optoelectronic solid state image converters have been proposed instead of the camera tubes. In addition to matrices comprised of photodiodes, recently also charge-coupled (CCD-) image converters have gained increasing significance, which, for example, are described in detail in the publication "Electronic Design", March 15, 1976, at pages 70-75.
Compared with television cameras having video pickup tubes, the television cameras constructed with solid state image converters can be kept smaller. Also, they exhibit a simpler circuit construction which is easy to integrate. However, the limited number of image (or picture) elements proves disadvantageous here. In the case of a video pickup tube, at least in the horizontal direction, the number of image elements can be considered as unlimited. In the vertical direction, the number of image elements corresponds to the number of scanning lines of the television system. By contrast, the number of image elements in the case of a solid state image converter is limited by the number of photodiodes, or charge elements, respectively.
In the case of the known CCD- image converters, a maximum number of 512.times.512 charge elements is present. If such a CCD- image converter is coupled with an x-ray image intensifier, then a degradation of resolution results as compared with a television installation with a video pickup tube. If, for example, an image intensifier of 17 cm-input diameter is scanned by such a CCD- image converter, a limit of resolution of approximately 1.5 line pairs per mm results.